Blood pressure can be defined as the pressure the blood exerts on the artery walls. It is measured in millimetres of mercury. There are two measurements associated with blood pressure. These are:
SYSTOLIC blood pressure. This is the pressure within the arteries when the heart is pumping, thus causing an increased volume of blood flow through the arteries and increasing the pressure within the arteries. Anxiety, exercise, food and caffeine affect it and it rises linearly with exercise.
DIASTOLIC blood pressure. This is the pressure within the arteries when the heart is in a relaxed state and the pressure within the arteries decreased. Since the diastolic blood pressure is the “relaxed” measure, it should be more stable and therefore, changes in this measure are usually significant in diagnosing contra-indications to exercise such as hypertension.
The diastolic blood pressure remains constant during exertion and is not immediately affected by food. However, over a period of time, it will rise in accordance with stress.
Medical guidelines state that a normal blood pressure for most adults is less than 120/80 mm Hg.
Ranges for the four blood pressure categories:
|
Category |
Systolic (top number) |
Diastolic (bottom number) |
|
|
<120 mmHg |
< 80 mmHg |
|
Pre-hypertension |
120–139 mmHg |
80–89 mmHg |
|
High blood pressure |
||
|
Stage 1 |
140–159 mmHg |
90–99 mmHg |
|
Stage 2 |
> 160 mmHg |
> 100 mmHg |
Note: When systolic and diastolic blood pressures fall into different categories, the higher category should be used to classify blood pressure level. For example, 160/80 mmHg would be stage 2 high blood pressure.There is an exception to the above definition of high blood pressure.
A blood pressure of 130/80 mmHg or higher is considered high blood pressure in people with diabetes and chronic kidney disease.